I finally got my programmer, bought it with custom tunes for 87 economy, 87 performance, 87 towing based on full information to the company of what, how, where, etc. Plan to use it for economy because of gas prices, towing for better performance with our travel trailer.
2 weeks ago my typical gas mileage was 14.5 MPG for going to work and back, running around town.
This week, yes, it does improve shifting and such, but my gas mileage has increased to....14.48 MPG. This was with the same roads traveled at the same speeds, etc. I would assume that besides lowering the shift points the air fuel was adjusted, but once up to speed, one can only move a rock at a certain speed with certain modifications, all things being equal.
Calculations performed with careful watching of speeds, starting and stopping, filling the tank, using a calculator to check the mileage both times.
I can only hope it will increase some and that in towing it will do good, as the stock truck had no really bad issues.
It is a truck, not a car.

 

Emailed Justin about the mileage today, he admitted that typical economy mileage would only be from .5 to 1 mpg typical driving. I had hoped to gain 2 mpg, to provide a cost payback in 1 years time.
Oh well, still have the use of it for towing.

 

I'm not getting your math in your first post. Maybe its me.

 

The value of a programmer is not in the fuel economy, but the much more responsive engine, improved shifting and downshifting, all without taking more fuel.

 

Very True BlueJay, but I only need the truck to be more responsive, shift better when pulling a travel trailer,, maybe 5% of time used in a year, rest of the time it is just used to get from point A to point B.

 

I was being factitious with wording Sawman. I had no fuel mileage improvement at this point, just better shifting, unless pushing it, the trucks in overdrive by about 45 mph, that is what economy mode is basically about.